Eric Horwitz, M.D., of the Fox Chase Cancer Center here said the Radiation Therapy Oncology Group (RTOG) trial had confirmed that two years of hormone therapy after radiation is the standard of care for patients with locally advanced, non-metastatic prostate cancer.

Reporting at American Society for Therapeutic Radiology and Oncology (ASTRO) meeting, Dr. Horwitz said 1,554 men with locally advanced prostate cancer had been enrolled into the trial in 1995. All patients received four months of hormone therapy before and during their radiation treatments.

"Our findings confirm what we saw five years ago with this study," Dr. Horwitz said. "When it holds up after 10 years, we know it is real."

After radiation treatment, the patients were randomized into two groups -- to receive 24 months of additional hormone therapy or to receive no further hormone therapy.

"At 10 years, the men receiving an additional 24 months of hormone therapy showed significant benefit over those not taking additional hormone therapy," Dr. Horwitz said.

Men with aggressive cancer, Gleason scores of 8 or higher, achieved a significant survival advantage if they were on hormone therapy even longer. If these patients took hormone therapy for two years longer than other men about 45.0% of then were still alive after 10 years compared with 31.9% who had shorter period of androgen deprivation therapy (P=0.0061).

Disease-free survival was 22.5% in the hormone therapy group compared with 13.2% in the patients who discontinued the therapy (P<0.0001).

Disease-specific survival was 88.7% for patients on hormone therapy compared with 83.9% not on the therapy (P=0.0042).

Distant metastases occurred in 14.8% of patients on hormone therapy compared with 22.8% of patients not on therapy (P<0.0001).

However, there was no statistically significant difference between the groups when it came to overall survival. There were 342 survivors among the 763 patients in the non-hormone therapy patients (44.8%) compared with 353 survivors out of the 758 hormone therapy patients (46.6%).

Cliff Robinson, M.D.Cleveland Clinic

In a second study, however, researchers at the Cleveland Clinic said their retrospective patient review questioned whether long-term use of the hormone therapy might have some untoward results. "We found there was a twofold increase in the risk of death among patients taking hormone therapy for longer than six months," said Cliff Robinson, M.D.

In his study, Dr. Robinson reviewed the medical histories of 579 men treated for prostate cancer at the Cleveland Clinic from 1998 to 2003, specifically enrolling men at high risk of prostate cancer recurrence following radical prostatectomy, brachytherapy, or external beam radiation.

"Specifically, we were looking for ways to improve outcomes of high risk patients," said co-author Chandama Reddy, M.S., a biostatistician. "We weren't looking to find something wrong with anti-hormone treatment, but these numbers just jumped out."

Dr. Robinson said that the five-year survival after definitive patients who had not received any post-procedure treatment was 92%.

Among the 351 patients who received treatment for one to six months, the survival rate was also 92%.

But among the 74 patients who took the anti-hormone treatment for longer than six months, the survival was 76%. (P=0.03)

"That's a significant difference," Robinson said.

In addition, Jay Ciezki, M.D., another co-author, said that with or without hormone therapy there did not appear to be any impact on prostate cancer recurrence.

Philip Devlin, M.D., of Harvard Medical School, acting as a spokesperson for ASTRO, said "the prospective RTOG study represents the highest level of evidence and indicates that there are certain benefits to receiving androgen deprivation therapy as far as preventing spread of disease and disease progression." He said the retrospective nature of the Cleveland Clinic trial raises questions but doesn't reach the same level of evidence.

Dr. Robinson suggested that differences in the population of the studies and differences in treatments -- especially in the dose of radiation used the RTOG study -- might have created some of the differences in outcomes.

He said, however, that the failure of the RTOG study to show an overall survival benefit indicates that there may be some other aspect of hormone therapy that may affect patients. He noted that recent studies found that hormone therapy increased risk of diabetes and cardiovascular disease.

The Cleveland Clinic researchers are now checking to determine the cause of death of the patients in the study, Dr. Robinson said.

Reviewed by Zalman S. Agus, MD Emeritus Professor at the University of Pennsylvania School of Medicine

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